Andre Laurence
Well-Known Member
In case you missed the video that we released last Friday... Can you increase the range of your EV with a simple change? Yes, it costs money, but the change is significant.
Video - Do smaller wheels actually increase range?
- Thread starter Andre Laurence
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There is a geometric challenge. Distance is usually wheel rotation counted. So the revolutions per mile is how cars tell how far a car has gone. Mount tires with a lower revs/mile and the calculated MPG is off (and speedometer.) For example, a smaller diameter wheel will indicate more miles traveled than true over the same route … better MPG.
A better metric is a GPS based speed and MPG metric BUT such software is too hard for most automobile ‘coders.’
Bob Wilson
A better metric is a GPS based speed and MPG metric BUT such software is too hard for most automobile ‘coders.’
Bob Wilson
Andre Laurence
Well-Known Member
Actually that is not correct. Most of my savings come from the fact that thses wheels are much, much lighter, which means less rotational mass and intertial resistance. In both of my EVs, I did the same thing on my previous EV, most of my savings actually came from city driving and it is a significant amount. I talk about it in this video.
Andre Laurence
Well-Known Member
Hi Bob, that is why you should never change the overall diameter of the wheel. I talk about this in the video. When you down size the wheel you have to increase the tire diameter to compensate. There is no difference in my speedometer or odometer because my overall wheel diameter has not changed.
I find the best practice is to compare App GPS metrics with the vehicle indicated.
Bob Wilson
Bob Wilson
Steadfast
Member
Did I get it backwards? Ha!
I was thinking about this as I had typed my response. I was going my memory and I was questioning myself as I posted my comment because it didn't make sense when I thought about inertia.
Depending on temperature above and below 13-14 C, I’m seeing between 6.4 and 8 km/kWh around town. Also after reading an SAE paper, my home-made wheel covers are now near zero flow and my benchmarks show about 7% improvement. With regenerative braking, very little brake pad heat is lost.
Tesla at one time sized all tires for the highest performance and heaviest Model 3/Y. So I switched to lighter wheels and lighter pickup tires for efficiency. Since I have only two wheel drive, I only replace one pair at a time.
Front tires go to rear drive wheels and new ones go on the front. Wear depth of the rear tires determines when I buy my next pair. Then I measure side-to-side tread depth of the four worn tires to identify alignment issues. I don’t do left-right swap tires as achieving 4-wheel alignment is part of my efficiency obsession.
New tires go on front and the former fronts go to replace the rear drive tires. This avoids a big tire bill and lets me get maximum distance on the tires. Just sometimes a favorite tire goes ‘end of life’ and there may be different brands that I choose front and rear.
I also go by an early truck scale measured weight to choose my replacement tires. Specs are nice but measured is best. So my efforts have saved about 28 kg of weight and reduced the moment of inertial (I.e. tire/wheel rotational inertia.)
For those curious, my best metrics show about 80-85% energy recovery from regenerative braking versus 100% friction loss from ordinary braking.
Bob Wilson
Ps. Retired engineer and efficiency fanatic.
Tesla at one time sized all tires for the highest performance and heaviest Model 3/Y. So I switched to lighter wheels and lighter pickup tires for efficiency. Since I have only two wheel drive, I only replace one pair at a time.
Front tires go to rear drive wheels and new ones go on the front. Wear depth of the rear tires determines when I buy my next pair. Then I measure side-to-side tread depth of the four worn tires to identify alignment issues. I don’t do left-right swap tires as achieving 4-wheel alignment is part of my efficiency obsession.
New tires go on front and the former fronts go to replace the rear drive tires. This avoids a big tire bill and lets me get maximum distance on the tires. Just sometimes a favorite tire goes ‘end of life’ and there may be different brands that I choose front and rear.
I also go by an early truck scale measured weight to choose my replacement tires. Specs are nice but measured is best. So my efforts have saved about 28 kg of weight and reduced the moment of inertial (I.e. tire/wheel rotational inertia.)
For those curious, my best metrics show about 80-85% energy recovery from regenerative braking versus 100% friction loss from ordinary braking.
Bob Wilson
Ps. Retired engineer and efficiency fanatic.
I get different highway and city benefits from the 16-inch (vs 17-inch) wheels on my MINI Cooper SE. The wheels provide better range on the highway, and the taller tire sidewalls (keeping the overall diameter constant) make for a much comfier ride through the potholed streets of my city.
On the one day a year (during Drive Electric Week) I mount the 17-inch, aerodynamic wheels, I'm shocked at how the 1-inch difference makes every pothole a scary proposition due to the reduced cushion from the tires' sidewalls. I'm not a skilled enough driver to benefit from the greater traction provided by the wider contact patch of the 17-inch tires. However, I'll admit that, in general, bigger wheels look better. I know 15-inch wheels that fit other MINIs won't clear my disk brake calipers, so I'm not tempted by that even less-attractive possibility.
On the one day a year (during Drive Electric Week) I mount the 17-inch, aerodynamic wheels, I'm shocked at how the 1-inch difference makes every pothole a scary proposition due to the reduced cushion from the tires' sidewalls. I'm not a skilled enough driver to benefit from the greater traction provided by the wider contact patch of the 17-inch tires. However, I'll admit that, in general, bigger wheels look better. I know 15-inch wheels that fit other MINIs won't clear my disk brake calipers, so I'm not tempted by that even less-attractive possibility.